The flag which is a gold cross on a black field is often flown on St David's Day either alongside or as a replacement to the traditional and widely known Red Dragon flag.
The new Wales change shirt will now form a direct bond with the nation's patron saint, who was a cleric from Pembrokeshire who died in around 590AD, and will be seen in action for the first time when Warren Gatland's men take on Canada at the Millennium Stadium in the Invesco Perpetual Series on Friday 14th November.
St David was known as a proud Welshman whose last words were said to have been: "Be joyful and keep your faith and your creed."
He is known to have made a pilgrimage to Jerusalem and is credited with performing miracles as he rose to prominence as a teacher and preacher and was eventually made an Archbishop.
Fans in the Welsh capital were given first sight of the new kit, modelled on stage by internationals Jamie Roberts, Robin Sowden-Taylor and Jonathan Thomas, as part of a day's activities to launch Under Armour's full range of apparel supplied to all national and age grade teams and on sale to fans in high street shops.
WRU academy players joined in an exhibition training session held by WRU national performance manager Huw Wiltshire outside the Capitol shopping centre on Queen street.
Fans were able to pick up training hints and tips, and took part in a range of activities including the Under Armour Performance Challenge and using scrum-half passing and lineout throwing equipment provided.
Roberts, Thomas and Wiltshire were also joined by Under Armour performance training guru, American Todd Durkin in meeting and greeting fans and answering individual questions.
"The responsibility we bear to this jersey and sense of duty to the nation is something we instil in the players who join the Wales team, so the symbolism of these new colours is very important," said Wales coach Warren Gatland.
"The players represent Wales around the world and they should be aware of the country's heritage and the part that rugby plays in that history.
"These days our players are elite, professional sportsmen, but the chance to represent Wales is still a powerful incentive for each and every one of them."
The new change jersey has been made to the same high specification as the home kit unveiled last week and is complete with 'dragon scale grippy' and unique breathable material.
The jersey also carries the St David's flag itself on the right sleeve and sports the word 'Hiraeth', meaning belonging, stitched into its collar.
"We hope this design will carry a special meaning to all the people of Wales," said Peter Mahrer, Under Armour President, Europe.
"We have worked hard to ensure our designs link closely with the history of this great nation and this particular shirt has a bond with one of the most famous Welshman of all time.
"The symbolism dates to a time of chivalry and heraldry when events took place which created important chapters in Welsh history.
"Rugby defines Wales as a nation and we are delighted to have been able to make that link in the design of this jersey."
The jersey will be available from £49.99 adult and £39.99 youth - see www.wru.co.uk for further details. The 'authentic' version - the version of the shirt which is exactly the same as that worn by players - is available for the first time in all sizes from small to XXL in the same quantity as the replicas, retailing at RRP £79.99 for short sleeve only.
The 'replica' version, which is a more practical fit for daily wear, but has the same look, retails at RRP £49.99 short sleeve - Men's or Women's cut - and £54.99 long sleeve.
Youth replicas are £39.99 short sleeve and £44.99 long sleeve and infant shirts are available for £39.99 from 0-6months in ranges up to 18-24 months.